Screening for Renovascular Hypertension

Two of our previous studies [1, 2] relate to Dr. Ruttimann and colleagues' interesting suggestion that smokers have a higher baseline renin value and an increased renin reactivity to captopril. First, we showed that smokers (also defined as persons who smoke 20 or more cigarettes per day) who are matched to nonsmokers for age, gender, and race had the same plasma renin activity values as nonsmokers [1]. In our recent second study, we showed that the bulk of false-positive captopril tests arise in patients whose baseline plasma renin activity value is elevated [2]. In contrast, among patients with normal and low renin activity values, specificity was 99%. In this study, only two of eight patients with a false-positive test result were smokers (unpublished data). Thus, we suggest that the exaggerated renin response leading to the false-positive captopril test results are related to the elevation of baseline renin rather than to smoking status.